Renal disorders in rheumatologic diseases: the spectrum is changing (part 2. Arthridides)

Proteinuria and hematuria as early signs of renal involvement in juvenile idiopathic arthritis

Objectives

To evaluate glomerular and tubular renal functions and analyze blood pressure in a cohort of pediatric patients with juvenile idiopathic arthritis (JIA).

Methods

A total of 40 pediatric patients, 20 (50%) with JIA and 20 (50%) healthy control subjects, were studied, and performed the renal function on 24-h collection and the 24-h ambulatory blood pressure monitoring (ABPM). Moreover, we compared renal function and blood pressure trends between the groups of JIA patients with different disease activities.

Results

No statistically significant differences were observed between patients with JIA and healthy children in terms of glomerular filtration rate (GFR), fractional excretion of sodium (FENa), tubular reabsorption of phosphate (TRP), and calcium-creatinine urine ratio (CaU/CrU). In contrast, we observed significantly higher values in JIA patients than in controls for the presence of hematuria (p < 0.0001) and proteinuria (p < 0.0001). Compared to the control group there were significantly higher values of hematuria and proteinuria/day in both groups of JIA patients with low disease activity (respectively, p = 0.0001 and p = 0.0002) and moderate disease activity (respectively p = 0.0001 and p = 0.0012). Systolic and diastolic dipping were significantly reduced in patients with JIA compared with healthy controls (p < 0.0001 and p < 0.0001, respectively).

Conclusions

Our study showed that children with JIA, already in the early stages of the disease, have higher values of hematuria and proteinuria, which are early warning signs of nephropathy. Therefore, detailed screening of renal function and pressure monitoring in patients are necessary to monitor their evolution over time.

Frequency of Renal Function Parameter Abnormalities in Patients with Psoriatic Arthritis and Rheumatoid Arthritis: Real-World Evidence from Clinical Practice

Objective: Patients with psoriatic arthritis (PsA) or rheumatoid arthritis (RA) commonly develop renal dysfunction due to either systemic inflammation or drug-related nephrotoxicity. This study compared renal function parameters in patients with PsA versus those with RA and examined the impact of clinical remission or disease relapse on renal function. Methods: This single-center retrospective study was conducted at the University Hospital of Messina, Italy. Adult patients (aged ≥18 years) with PsA or RA who attended the rheumatology clinic within the past 6 months were identified from electronic medical records. Results: In total, 45 patients with PsA (n = 23) or RA (n = 22) were included. The mean (standard deviation) age was 55.6 (15.9) years, and 78% of participants were female. Patient age, renal function, and medical history were generally similar between the two disease groups, although significantly more RA patients were smokers, and more PsA patients had comorbid hypertension. The prevalence of estimated glomerular filtration rate [eGFR] ≤90 mL/min/1.73 m² at 1, 6, and 12 months of treatment ranged from 38.5% to 58.3% in the PsA group and from 45.5% to 54.5% in the RA group and did not significantly differ between disease groups. Clinical remission did not appear to affect renal function parameters in either disease group; however, relapse was associated with significantly higher serum creatinine levels in PsA patients at the same timepoint. Conclusion: In this study, patients with PsA and RA had a similar prevalence of renal function parameter abnormalities over 12 months of treatment. Disease relapse may impact renal function in patients with PsA.